Method: Sequel::Postgres::DatabaseMethods#with_advisory_lock

Defined in:
lib/sequel/adapters/shared/postgres.rb

#with_advisory_lock(lock_id, opts = OPTS) ⇒ Object

Attempt to acquire an exclusive advisory lock with the given lock_id (which should be a 64-bit integer). If successful, yield to the block, then release the advisory lock when the block exits. If unsuccessful, raise a Sequel::AdvisoryLockError.

DB.with_advisory_lock(1347){DB.get(1)}
# SELECT pg_try_advisory_lock(1357) LIMIT 1
# SELECT 1 AS v LIMIT 1
# SELECT pg_advisory_unlock(1357) LIMIT 1

Options:

:wait

Do not raise an error, instead, wait until the advisory lock can be acquired.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 916

def with_advisory_lock(lock_id, opts=OPTS)
  ds = dataset
  if server = opts[:server]
    ds = ds.server(server)
  end

  synchronize(server) do |c|
    begin
      if opts[:wait]
        ds.get{pg_advisory_lock(lock_id)}
        locked = true
      else
        unless locked = ds.get{pg_try_advisory_lock(lock_id)}
          raise AdvisoryLockError, "unable to acquire advisory lock #{lock_id.inspect}"
        end
      end

      yield
    ensure
      ds.get{pg_advisory_unlock(lock_id)} if locked
    end
  end
end